The 17th November is when your next 90 day report is due, the extension of stay application doesn't count as a 90 day report unless it is the first extension, has been like this for years.
As your son was born after 1st July 2006 then there is no requirement for you to be married nor will any DNA test be required. Follow the guidance in this document, paying particular attention to tables A & C. I assume that you are named as the Father on his Thai birth certificate? This will need translating in to English, as will any other Thai documents, as has been mentioned before by other posters. OS_Guidance_G3_10.16.pdf